Hey guys. I got the car 2 months ago and I finally used the AC for the first time the other day. I noticed that when the AC is on the car idles rough. I notice it mostly on the steering wheel and brake pedal when stopped. I've driven 4cyl cars before and never noticed so much vibration from the AC running. The dealership told me it was normal but it doesn't feel normal, nor do I ever believe what the dealership say while the car is under warranty. When the AC is first turned on to I can hear this slight wooshing sound coming from the engine compartment that slowly speeds up until it finally can not be distinguished. Any ideas what I should take a look at? Other then that the AC works great.

 

Look to see if idle speed is dropping significantly when AC compressor engages. Normal rpm should be about 750 +/- 50 rpm, and it should remain steady when compressor engages. If the idle speed drops perhaps 150-200 rpm, the engine vibration will be noticeably worse. The problem is usually blockage of the idle air control valve (IACV) due to carbonbuildup on the IACV inlet screen. It could also be due to a dirty throttle plate blocking idle air flow severely. Clean IACV and throttle plate w/ throttle body cleaner. It could also be a defective IACV that has an open solenoid which will require replacement of the IACV.

good luck